Scientists seem to have found a kink in the armour of super gonorrhea. In a large-scale clinical trial reported this month, the experimental drug zoliflodacin was found to be just as effective as other frontline antibiotics at treating the stubborn bacterial infection. The results will pave the way for zoliflodacin to become a crucial tool in the never-ending arms race against antibiotic resistance.
Gonorrhea, caused by the bacteria Neisseria gonorrhoeae, is one of the most commonly reported sexually transmitted infections worldwide. Not everyone who catches it will become sick, but its symptoms can be plenty disturbing and include puke-coloured genital discharge, bleeding urination, swollen testicles in men, and further bleeding between periods for women. If left untreated, it can also cause infertility, raise the risk of catching other STIs, and even lead to complications like blindness in newborns who get the infection from their mothers.
The disease was once easily treatable with penicillin. But over the years, gonorrhea has steadily evolved to resist nearly all antibiotics commonly used against it. More recently, doctors have started to encounter cases of gonorrhea that show resistance to even these last remaining drugs. There are many other drug-resistant germs out there, but gonorrhea could become one of the first superbugs to widely spread among the community in the not-so-distant future.
The ongoing crisis of antibiotic resistance has left many scientists and research organizations scrambling to develop new drugs for infections like gonorrhea. Ideally, these drugs would not only work as intended but also attack infections in a way that’s different from existing antibiotics, extending the time it would take for the bacteria to develop resistance to them. And it seems that zoliflodacin has fulfilled both these criteria.
The drug is being developed by the non-profit organization Global Antibiotic Research & Development Partnership (GARDP), in collaboration with Entasis Therapeutics, an affiliate of the drug company Innoviva. On Wednesday, GARDP announced the results of their latest and largest study of zoliflodacin, a Phase III clinical trial.
The trial involved over 900 people in five countries, including the U.S., who were diagnosed with uncomplicated gonorrhea, or an infection without other relevant risk factors for serious illness, like pregnancy. These patients were randomly assigned to receive a single oral dose of zoliflodacin or a combination of the two antibiotics ceftriaxone and azithromycin, a common frontline treatment for gonorrhea (Some countries like the U.S. have started to only recommend ceftriaxone as a treatment for gonorrhea, thanks to growing azithromycin resistance).
The trial met its primary goal, with zoliflodacin appearing to clear these infections just as well as ceftriaxone and azithromycin. The drug also seemed to be well-tolerated and there were no serious adverse events or deaths linked to its use reported. Other research has found that zoliflodacin uses a novel mechanism to kill gonorrhea bacteria and that it can fend off drug-resistant strains, meaning these results are even better than they might look at first glance.
“The outcome of this study is a potential game changer for sexual health,” said Edward W. Hook III, protocol chair of the study and an emeritus professor of medicine at the University of Alabama, in a statement provided by GARDP. “In addition to the potential benefits for patients with infections with resistant strains of Neisseria gonorrhoeae, the potential lack of cross-resistance with other antibiotics and the oral route of administration will simplify gonorrhea therapy for clinicians worldwide.”
The findings will have to be vetted by outside scientists and regulatory agencies. But assuming everything is validated, zoliflodacin should be on the fast track to drug approval. From there, it would become the first new drug for gonorrhea successfully developed in decades. It’s also been studied as a treatment for other STIs like chlamydia.
GARDP has already obtained rights to commercialize the drug in three-quarters of the world, including most low- to middle-income countries, while Entasis will hold rights in the major markets of the rest, including the U.S. Ideally, this would mean that zoliflodacin will be relatively affordable in the places where it’s needed most. Another important consideration will be the need to ration the drug and use it only when other treatments won’t work, in order to ensure that resistance to it stays low for as long as possible.
“We cannot deprive people who need this treatment around the world,” Manica Balasegaram, GARDP’s executive director, told Nature.